Automatic flow regulator



Jan. 14, '1964 K. NELSON ETAL AUTOMATIC FLOW REGULATOR Filed Aug. 31, 1960 Ill JI'..

1N VEN TORS Kuri Nelson By 'VQZI A. SCO Daw, JW@ ww www ATTORNEYS EG. l 'A United States Patent "O M7590 AUTMATIC FLW REGULATOR Kurt Nelson and Walter A. Scott, Poughkeepsie, N.Y., as

signor-s to The De Laval Separator Company, Poughkeepsie, N Y., a corporation of New Jersey `Filed Aug. 3l, 196i), Ser. No. 53.178 5 Claims. (Cl. 137-504) This invention relates to flow regulators and has particular reference to an improved regulator for automatically maintaining a substantially constant rate of lluid lloiv in a closed system.

There are many instances in which it is desired to supply a liquid through a closed system under pressure at a constant ow rate, despite variations in the feed pressure or back pressure in the system. An example is a system including one or more centrifugal separators of the hermeticaliy closed type fed through a supply pipe line from a supply tank, as by means oi a centrifugal pump. In this instance, it is necessary to maintain the supply of liquid at a substantially constant predetermined flow rate in order to provide good operating efclency of the centrifuge or cent uges. ri-hus, il one of two centrifuges fed by the supply line should be shut down, tl ereby increasing the bscl'. pressure on the supply line, the other separator will not operate peak e i ciency unless some measure is taken to counteract the resulting change in the pressure drop across this centriiuge.

Various attempts have been made heretofore to provide means for automatically regulatinv the llew of liquids throi' closed systems such as that described above, in order to maintain a substantially constant rate. of llow. rlhese prior attempts, insofar as we are aware, have not been successful, either because the regulating apparatus been too complicated and expensive for most purposes or because it has been unreliable in operation.

The principal object of the present invention is to provide an automatic regulator for maintaining a substantially constant rate ot ll in a closed system and which is simple in construction and reliable in operation.

A regulator made according to the invention comprises a housing having fluid outlet, and a slide valve forming a iluid inlet passage leading into the housing, the housing dening a tlnoughflow chamber interconnecting the inlet passage and the outlet. The slide valve includes a pair of telescoping members having a loose sliding lit, one or these valve members being lined to the housing and the other valve member being slidable in the direction of now through the chamber to gradually reduce the throughlliw area of the inlet passage, the slidable valve member being iased by a substantially constant force in the direction opposite to the flow direction and toward a fully open position in which the inlet passage has a maximum throughnew arc-a. A movable disc is located in the housing charnber and has a surface against which fluid from the inlet passage is adapted to impinge in flowing to the outlet, thereby urging 'he disc in the flow direction against the constant biasing torce, the disc and the surrounding wall of the chamber forming a generally annular throughflow space in the chamber. Means are provided for connecting the slidable valve member to the disc for movement therewith in the two directions noted above.

With this construction, the biasing force on the sliduble -Je member holds the latter in its fully open position u ien the llow rate through the inlet passage is relatively low or zero. However, as the liquid `flows at increasing rate through the inlet passage and thereby impinges on the disc with greater force, the disc moves the slidable valve member in the direction to reduce the throughllow area of the inlet passage, until the movable parts are in a state of balance in which the constant biasing force tending to increase the througlillow area of the inlet passage is equal to the force exerted by the throughliowing liquid on the disc and tending to reduce this throughlow area. The rate of ilow corresponding to this equilibrium position will depend upon the maenitude of the constant biasing force and the effective area of the disc against which the lluid impinges in flowing through the housing, as well as the ratio oi this area to the throughliow area of that portion of the housing chamber in which the disc is movable.

An important feature of the new regulator, and one on which its successful operation depends, resides in the disc being operatively connected to a slide valve of the type describe-d and the provision ot the loose sliding lit between the telescoping parts of the slide valve. A valve of this construction imposes negligible resistance to movements E the sliding valve member for varying the throughllow area of the inlet passage; and the loose sliding lit prevents binding of the slidab-le valve member on the fixed valve member while permitting liquid from the inlet passage to enter the small clearance between the telescoping valve members and form a lubricating film. Preferably, the disc is connected to the slidable valve member through a rod which is adapted to tilt relative to the slide-.ble valve member, as in this way binding of the valve members is prevented because the dis; can move laterally in the housing chamber without to tilt the slidable valve member relative to tbe fixed valve member. Normally, the flow of through the housing chamber and around the disc acts to center the disc in the annular space between the latter and the surrounding wail oi the housing chamber'.

ln the preferred construction, the fixed valve member projects into the housing toward the outlet and is surrounded by the slidable valve member, the latter forming with the surrounding wal oi the housing a substantially annular space; and the fixed valve member has an external annular groove forming part of the inlet passage and located adjacent generally longitudinal slots in the slidable valve member, these slots also forming parts of the inlet passage. Thus, as the slidable valve member moves from its fully open position toward the outlet, the slots therein forro a progressively decreasing throughiiow area through which the lluid can pass into the housing charnber from the annular groove in the fixed valve member. To permit the regulator to accommodate dilrerent throughllow rates which are to be maintained substantially conetant, the disc is releasably connected to the slidable valve member so that the disc can be replaced with one of larger or smaller diameter.

For a better understanding oi the invention, reference may be had to the accompanying drawings, in which FIG. l is a vertical sectional view of a preferred form or" the new rflow regulator, showing the slide valve in its fully open position;

2 and 3 are sectie al views on lines 2 2 and iii- 3, respectively, in FlG. l; and

FIG. Il is a vertical sectional View of the lower portion of a modified form of the regulator.

Referring to FIGS. 1 3, the regulator here shown comprise-s a housing lil 'in the form of a vertical pipe which is enlarged at its lower portion, the upper end of 'the housing being open to form a liquid outlet il. A hollow fitting l2 is releasably secured to the housing at its lower end, by means of a releasable clamp i3 engaging external flanges on the housing and the fitting. An annular gasket if is inserted between the opposing lace of these llanges to form a liquid-tight seal when the pmts are clamped together by the clamp i3.

The litting l2 has a generally cylindrical stern portion l5 projecting upwardly into the housing in spaced relation to the surrounding wall of the housing. rlhe hollow interior lo of this litting forms a chamber opening through the bottom of `the ltittinsy and terminating at its upper end well below the top of the stem portion 1S. At its upper portion, the litting chamber 16 communicates through latenal holes 17 with lan annular groove t8 formed in the outer wall of stem portion 15. As shown in FEG. 2, there are six holes 17 spaced equidistantly around the upper portion of chamber 16 and leading into the lower portion of the annular groove 18, which forms an annular ilow channel.

The fitting 12-13 forms -in elect a stationary or fixed valve member coacting with a slidable valve member Ztl. The latter is of generally cylindrical form, open at the bottom, land receives Ithe fixed valve member with a loose sliding fit. Intermediate its ends, the slida'ole valve member 26 has vertical slots 21, there being three of these slots spaced equidistantly yaround the member Ztl as shown in FlG. 2. The slots 2l correspond in length to the width of the annular groove 1.8; and when the slidable valve member 2d is in its lowermfost position, with its upper end resting on top of the stem portion l5, the upper and lower ends of slots 2l are opposite the upper and lower edges, respectively, of the lannular groove 18, as shown in FIG. 1.

As will be apparent from the foregoing, the chamber 16, holes 17, groove 18 and slots 21 form inlet passages leading into the lower portion of housing 10, and these passages will have their maximum throughllow areas when the slidable valve member Ztl is in its lowerrnost position shown in FIG. 1. However, as the member 293 is raised relative to the iixed valve member or stem 15, the total throughliow area of these inlet passages will be gradually reduced due to the fact that the vertical slots Z1 will each have a progressively decreasing length in registry with the annular groove 15. Thus, the telescoping members 15 and 243 constitute a slide valve forming fluid inlet passages leading linto the housing, which passages are variable as to total throughllow area by vertical movements `of the slidable valve member 2th The fitting 12 is externally threaded at its lower portion, as shown at lla, so that it can be connected to a suppl-y pipe (not shown) from which liquid can be fed into the housing through these inlet passages; Iand the housing 10 forms a chamber .10a interconnecting these inlet passages with the housing outlet 11.

The slidable valve member 2t) is provided at its upper end with a central hollow boss 22 which loosely receives the reduced lower end portion of a vertical rod 23. The hollow boss Z2 is out away at opposite sides, substantially below its upper end, to receive the legs of -a U-shaped spring clip 24, these legs being engaged in an annular groove 23a in the 4reduced lower portion of rod 23. The clip 2A- thus forms a releasable means for connecting the rod 23 to the slidable valve member 20 so that these parts will move with each other vertically in the housing. One of the legs of the clip `24 is provided at its end portion with ka detent 2da to prevent accidental withdrawal of the clip from the rod groove 23a.

At its upper end portion, the rod 23 carries a circular disc 26, which may be integral with the rod. As shown in FIG. 1, a similar `disc 26a is carried by the rod above the disc 25 but in spaced relation thereto. The discs 2o- 26a are substantially smaller in diameter than the internal diameter of the upper portion of the housing 10'. This upper portion of the housing is of uniform internal diameter, so that there will be la uniform clearance space around the discs 26-26a throughout their range of vertical movements Iin the housing. Upward movement of the slidable valve member and rod 23 -is limited by engagement of the upper disc a with a perforated stop 27 secured in the housing at its upper portion.

The upper end of slidable valve member Z0 is ported by means of a series of holes 2S, for a purpose to be described presently. As shown in FIG. 3, there are six holes 28 spaced equ-idistantly around the hollow boss 22.

Still referring to NGS. 1 3, assume that a milk pipe line including a centrifugal pump (not shown) is connected to the regulator inlet through the fitting l2 and that the regulator outlet 11 is connected through a pipe to Ia centrifugal separator of the hermetically closed type (not shown) which is to be supplied with milk; at a rate of 15,000 lbs. per hour to provide good operating eiciency of the centrifuge. Before the milk is fed to the regulator, the slidable `valve member 2t) is in its lowermost or fully fopen position to which it is biased by the weight of the .parts Ztl-26a. In other words, the action of grav-ity serves as a constant force biasing these movable parts toward the fully open position of the slide valve. When the feed of mil-k to the regulator is started under the action of the centrifugal pump, the milk will ow through the regulator and toward the centrifuge inlet at a rate which builds up Itoward the desired rate, the milk issuing from the slots 21 first lling the lower portion of chamber vlila and then passing through the clearance space around the discs 21o-26u and through the regulator outlet 1l to the centrifuge inlet. At some point during this build-up of the tlow rate, the force of the upwardly owing milk impinging on the lower surface of the discs 26-26u will be suicient to overcome the constant biasing force which urges the parts Z9-26a toward their lowermost positions, whereupon the slidable valve member Ztl will be raised so as to reduce the total throughflow area of the inlet slots 21. This upward movement of the parts, with consequent reduction of the total throughflow area of the inlet passages, will continue until the dow rate reaches the desired value of 15,006 lbs. per hour, at which time the upward force of the milk exerted on the movable parts including discs 26-26a will equal the constant downward biasing force on the movable parts so that a state of equilibrium is reached. The movable parts will then oat in their equilibrium positions (as lon-g as the pressures at the inlet and outlet of the regulator remain constant) so as to maintain fthe desired flow rate through the partially restricted inlet slots 21.

If the flow rate should increase above the desired value, as due to a decrease in the back pressure at the regulator outlet or an increase in the feed pressure at the regulator inlet, the resulting increase in the upward force of the liquid impinging on the lower surfaces of discs 26-26a will raise the valve member Ztl further so as to further reduce the effective total throughllow area of the inlet slots 21, thereby reducing the throughflow rate to the desired value and establishing a new equilibrium position of the movable parts if the decreased back pressure or increased feed pressure persists. Conversely, an increase in back pressure at outlet lll or a decrease in the feed pressure at inlet itting 12, resulting in a decrease oi the dow rate from the desired value, will reduce the force of the upwardly flowing milk impinging on the discs 26-26a and cause a lowering of the movable parts Zll-Za with a consequent increase in the total throughllow area of the inlet slots 21, until the flow rate increases to the desired Value.

It will be observed from the foregoing that the regulator automatically maintains a substantially constant flow rate despite a change in the back pressure at outlet 1l or a change in the feed pressure at the inlet fitting l2. Such a pressure change, resulting in a variation of the flow rate through the regulator, will immediately cause a raising or lowering of the movable parts 2tl- 26@ and a corresponding change in the elfective total throughilow area of the inlet slots 21 until the movable parts reach a new equilibrium position which restores the desired throughtlow rate and which corresponds to the new conditions imposed by the aforementioned pressure change tending to increase or decrease the flow rate from its desired value. During this operation of the regulator, the movable parts 20-26a are highly sensitive to changes in the flow rate and can readily move vertically to different positions for maintaining the desired f ow rate as described, because there is negligible friction between the valve members and 20. More particularly, the loose connection of rod 23 to valve member 20, provided by the spring clip 24, permits the discs 26-26a to move laterally to a certain extent in the housing chamber (incident to centering themselves in the stream of milk owing upward through this chamber) without tilting the slidable valve member relative to the fixed valve member 15, which would cause a binding action between these parts. In other words, because of the llexibility of spring clip 24 and also its loose t in the parts which receive it (FIG. 4), the discs 26-26tz are loosely connected to slidable valve member 20 through connecting means including the rod or element 23 which is tiltable laterally in all directions relative to slidable valve member 20 to prevent such binding action. Also, the loose sliding lit between the telescoping valve members 15 and 20 serves to prevent binding of these parts and provides for a film of milk between these parts which serves as a lubricant. For this purpose, a dilierence of 0.15 mm. between the external diameter of xed valve member 15 and the internal diameter of slidable valve member 20 has been found to provide the desired looseness of tit. Because of the annular groove 18, there is no need to provide means for preventing rotation of slidable valve member 20 relative to fixed valve member l5, which means would tend to restrict the freedom or movement of the movable parts Ztl-26a. That is, any rotation of valve member 20 relative to valve member 15 is of no consequence because the inlet slots 21 will always be in direct communication with the annular groove 18.

It has been found that operation of the regulator is greatly improved by providing the series of holes 23 in the upper end of slidable valve member 20. Without these holes, apparently milk llowing upwardly from the inlet groove 18 through the small clearance space between the valve members 15 and 29 builds up a pressure against the top of member 2d, due to inability of the milk to escape freely enough through the clearance space between the rod 23 and the surrounding hollow boss 22, and this build-up of pressure tends to result in false actuations of the movable parts Ztl-2da. However, by port'ag the top of member 20 with a substantial number of holes 2S, the milk can flow relatively freely in the upward direction between the valve members 15 and 20 aid out through the holes 28, thereby preventing any possible impairment of the desired movements of the parts 2li-26a.

The regulator shown in FIGS. l-3 is particularly adapted for uses in which there is a relatively low minimum pressure drop across the regulator and in which the ilow rate does not exceed about 20,000 lbs. per hour. In cases where the ilow rate exceeds this value, with a relatively high minimum pressure drop across the regulator, the modification shown in FIG. 4 is preferred. As shown in FIG. 4, the regulator is identical to that illustrated in FIGS. l-3 except that the holes 2S are omitted and instead a series of annular grooves 30 is provided in the periphery of the iixed valve member 15 at its upper portion. Thus, the grooves 30 form a labyrinth between the upper portions of the valve members 15 and il which Serves to greatly restrict the flow of milk upwardly between these members from the inlet groove 1S toward the clearance space between rod 23 and the surrounding boss 22. With the greater ow rates through the regulator, the holes 2S of FIG. l are apparently insulllcient to allow the milk to escape rapidly enough from the clearance space between the valve members 15 and 24) to prevent the undesirable action previously described. In the FIG. 4 embodiment, this difliculty is overcome by adopting the substmtially opposite expedient of preventing milk from reaching the underside of the top of valve member 20 at a rate such that it cannot escape freely through the hollow boss 22. The grooves 30 constituting the labyrinth can be formed in either the inner valve member 15 or the outer valve member 20, but in either rf6 case it serves to prevent any substantial leakage of milk upwardly through the small clearance space between the upper portions of the members 15 and 20.

In the use of either of the illustrated forms of the new regulator, the pressure at the inlet tting 12 should be at least 5 lbs. per square inch greater than the pressure at the inlet of the centrifuge or other apparatus to be fed through the regulator. An increase in this pressure differential will not adversely ailect the regulator operation, but any substantial decrease in this pressure differential will cause improper operation of the regulator through failure to maintain the desired throughtlow rate.

An example of the dimensions of a regulator made according to FIGS. l-3, for maintaining a fixed tlow rate of 15,000 lbs. of milk per hour with a minimum pressure drop of about 5.5 lbs. per square inch across the regulator, is as follows: The reduced upper portion of housing 10 has an internal diameter of 47.8 mm., the discs 2626a each have an external diameter of 39.15 mm., the enlarged lower portion of housing 10 has an internal diameter of 73.0 mm., the valve member 20 has an external diameter (exclusive of its enlarged lower portion) of 49.0 mm. and an internal diameter of 44.5 mm., the stem portion 15 of the iixed valve member has an external diameter of 44.35 mm., each of the three inlet slots 21 has a length of 36.0 mm. and a width of 4.7 mm., and the parts of the inlet passage leading up to these slots provide a substantially greater throughllow area than the slots when fully exposed. rl`he height of the enlarged lower portion of housing chamber lila is about mm. and the height of the slidable valve member 20 is about 130 mm. exclusive of the hollow boss 22;.

The ilow rate to be maintained constant by the regulator can be readily varied by replacing the discs 26 26a. with discs of larger or smaller diameter. Such re placement can oe effected easily by removing the lower clamp 13, withdrawing the parts 12 and 211 from the housing, detaching the rod 23 from part 20 by Withdrawing the spring clip 24, connecting a new rod 23 (with discs 21S- 25a of the desired dilierent size) to valve member 2i? by replacing the spring clip 24, and reassembling the parts in the housing. Discs 24E-Zta of larger diameter will cause a lowering of the llow rate to be maintained constant by the regulator. F or instance, in the eX- ample given above, wher the flow rate is iixed at 15,000 lbs. per hour with discs 12e- 26a having a diameter of 39.5 mm., discs having a diameter of 41.7 mm. will maintain a flow rate of 10,000 lbs. per hour and discs having a diameter of 36.6 mm. will maintain a ow rate of 20,000 l s. per hour. For the llow rates of 10,000 and 20,000 lbs. per hour, the minimum pressure drop across the regulator should be 2.5 and l0 lbs. per square inch, respectively. To maintain a flow rate of 25,000 lbs. per hour with the FIG. 4 embodiment, discs Zd 2da having a diameter of 34.4 mm. are used, and the minimum pressure drop across the regulator should be l5 lbs. per square inch. In all of these examples, the rod 23 is assumed to have a diameter of 16 mm.

While we have described the operation of the regulator in connection with the supply of milk to a centrifuge, it is to be understood that the regulator is adapted for other uses as well.

We claim:

l. An automatic flow regulator comprising a housing having a fluid outlet, a slide valve forming a fluid inlet passage leading into the housing, the housing defining a throughilow chamber interconnecting said inlet passage and outlet, the slide valve including a pair of telescoping members having a loose sliding fit, one of said valve members being llxed to the housing, the other valve member being slidable in the direction of ilow through the chamber to gradually reduce the throughflow area of the inlet passage, said slidable member being biased by a substantially constant force in the direction opposite to said ilow direction and toward a fully open position in which said 7 passage has a maximum throughflow area, a movable dise located in said chamber and against which fluid from the inlet passage is adapted to impinge in ilowing to said outlet, thereby urging the disc in said ow direction against said biasing force, the disc and the surrounding wall of the chamber forming a generally annular throughflow space in the chamber, and means connecting the slidable valve member to the disc for movements therewith in said directions, whereby the throughflow area of the inlet passage is reduced as the iluid therefrom impinges on the disc with greater force, said connecting means forming a loose connection and including an element tiltable laterally in all directions relative to said slidable valve member to permit lateral movements of the dise in all directions in said annular throughow space and thereby prevent binding of the slidable valve" member on the fixed valve member, the slidable valve member being freely rotatable relative to the fixed valve member, said fixed valve member having an annular groove forming part of said inlet passage.

2. A regulator' according to claim 1, in which said fixed valve member projects into the housing toward the outlet, the slidable valve member surrounding the fixed valve member and forming With the surrounding wall of the housing a substantially annular space.

3. A regulator according to claim 1, in which said element of the connecting means is a rod releasably secured to the sliclable valve member.

4. A regulator according to claim 1, in which the slidable valve member surrounds the fixed valve member, the slidable member also having an end facing the dise and ported to permit free escape of uid owing from the inlet passage along said loose t between the mern bers.

5. A regulator according to claim 1, in which the slidable valve member surrounds the xed valve member, the slidable member also having a substantially closed end facing the disc, one of said members forming a labyrinth in said loose fit between the members, the labyrinth being located between the inlet passage and said substantially closed end.

References Cited in the file of this patent UNITED STATES PATENTS- 400,173 Bell Mar. 26, 1889 829,669 Porter Aug. 28, 1906 1,087,906 Houghton Feb. 17, 1914 2,584,418 Branson Feb. 5, 1952 2,800,919 Kates Iuly 30, 1957 

1. AN AUTOMATIC FLOW REGULATOR COMPRISING A HOUSING HAVING A FLUID OUTLET, A SLIDE VALVE FORMING A FLUID INLET PASSAGE LEADING INTO THE HOUSING, THE HOUSING DEFINING A THROUGHFLOW CHAMBER INTERCONNECTING SAID INLET PASSAGE AND OUTLET, THE SLIDE VALVE INCLUDING A PAIR OF TELESCOPING MEMBERS HAVING A LOOSE SLIDING FIT, ONE OF SAID VALVE MEMBERS BEING FIXED TO THE HOUSING, THE OTHER VALVE MEMBER BEING SLIDABLE IN THE DIRECTION OF FLOW THROUGH THE CHAMBER TO GRADUALLY REDUCE THE THROUGHFLOW AREA OF THE INLET PASSAGE, SAID SLIDABLE MEMBER BEING BIASED BY A SUBSTANTIALLY CONSTANT FORCE IN THE DIRECTION OPPOSITE TO SAID FLOW DIRECTION AND TOWARD A FULLY OPEN POSITION IN WHICH SAID PASSAGE HAS A MAXIMUM THROUGHFLOW AREA, A MOVABLE DISC LOCATEDIN SAID CHAMBER AND AGAINST WHICH FLUID FROM THE INLET PASSAGE IS ADAPTED TO IMPINGE IN FLOWING TO SAID OUTLET, THEREBY URGING THE DISC IN SAID FLOW DIRECTION AGAINST SAID BIASING FORCE, THE DISC AND THE SURROUNDING WALL OF THE CHAMBER FORMING A GENERALLY ANNULAR THROUGHFLOW SPACE IN THE CHAMBER, AND MEANS CONNECTING THE SLIDABLE VALVE MEMBER TO THE DISC FOR MOVEMENTS THEREWITH IN SAID DIRECTIONS, WHEREBY THE THROUGHFLOW AREA OF THE INLET PASSAGE IS REDUCED AS THE FLUID THEREFROM IMPINGES ON THE DISC WITH GREATER FORCE, SAID CONNECTING MEANS FORMING A LOOSE CONNECTION AND INCLUDING AN ELEMENT TILTABLE LATERALLY IN ALL DIRECTIONS RELATIVE TO SAID SLIDABLE VALVE MEMBER TO PERMIT LATERAL MOVEMENTS OF THE DISC IN ALL DIRECTIONS IN SAID ANNULAR THROUGHFLOW SPACE AND THEREBY PREVENT BINDING OF THE SLIDABLE VALVE MEMBER ON THE FIXED VALVE MEMBER, THE SLIDABLE VALVE MEMBER BEING FREELY ROTATABLE RELATIVE TO THE FIXED VALVE MEMBER, SAID FIXED VALVE MEMBER HAVING AN ANNULAR GROOVE FORMING PART OF SAID INLET PASSAGE. 